影响对叶榕及其传粉者繁殖的生态学因素

在西双版纳,分别统计了对叶榕(Ficus hispida)雌花期雌雄果的进蜂量和花后期雌雄果繁殖的多个特征值,以此来探讨自然条件下,影响对叶榕及其传粉榕小蜂(Ceratosolen solmsi marchali)繁殖的因素。结果表明:单果内有效进蜂数量是影响种子生产和传粉榕小蜂繁殖的首要因素,而雌花期进果的传粉榕小蜂并不是都能全部进入果腔传粉或产卵,大部分蜂还未进到果腔就被夹死在顶生苞片层的通道里,能进入雌果内传粉的榕小蜂为(2.72±2.04)只·果^-1,约占总进蜂量的52%;而在雄果里,能进入果腔的蜂量只有(2.08±1.65)只·果^-1,占35%左右。由于雌果内的雌花显著比雄果内的雌花多,结合单果进蜂量雌多雄少的格局,最终单果生产的种子数量 (1 891.63 ± 471.53)比传粉榕小蜂的数量 (367.20 ± 208.02) 多5倍有余。在雌果里,供给传粉的雌花数量与所生产的种子数量之间呈显著的正相关,而没有接受到花粉或不能正常受精的雌花数量与种子数量呈显著的负相关。雄果不仅生产花粉,也是传粉榕小蜂繁殖的场所,在相关于传粉榕小蜂自身繁殖力的因子中,传粉榕小蜂产卵制造的瘿花数量对其种群数量有最大的影响;影响次之的是发育过程中死亡的个体数量,它可降低30%左右的传粉榕小蜂数量;影响排在第三位的是寄主的雌花数量。此外,3类非传粉者的存在,单果内平均可减少30多只传粉小蜂。     

小果野芭蕉种子散布和不同时空尺度上种子被捕食格局

 以分布在云南西双版纳地区的大型先锋草本植物小果野芭蕉(Musa acuminata)为研究材料,研究其种子初次散布过程和不同时空尺度上种子被 捕食格局。小果野芭蕉的成熟果实有75%在夜间被取食和传播,在白天消失的果实则占25%。蝙蝠是其最主要的种子传播者,鸟类在其种子传播 过程中也起到一定的作用。人工摆放种子试验结果显示小果野芭蕉种子的主要转移者是小型啮齿类(鼠类)和蚁类：在开放处理下3 d后转移率为 86%,排除蚁类(鼠类可进入)处理下种子转移率为69%以及排除鼠类(蚂蚁可进入)处理下种子被转移率为56%。季节、地点和生境均显著影响人工 摆放种子被转移强度：雨季显著高于旱季(p<0.001), 野芭蕉生境显著高于与其相连的自然森林和荒地(p<0.001),在人为干扰较少的补蚌自然 保护区显著低于西双版纳热带植物园和新山,而后两者之间并无显著差异(p>0.05)。同时,地点和生境以及季节、地点和生境都有显著的交互 作用。与相邻的森林和荒地相比,野芭蕉群落中种子被鼠类捕食的强度最大且受蚁类二次转移的比例最少,森林和荒地中种子被鼠类捕食的强 度相对较小且蚁类对种子的二次转移比例较高,从而更好地帮助种子逃避鼠类捕食。因此,依赖于食果动物(主要是蝙蝠, 也包括鸟类)的初次 散布是小果野芭蕉种子逃避捕食的关键。     

WATER POTENTIAL,TEMPERATURE, AND KINETIN EFFECTS ON SEED GERMINATION IN SOIL AND SOLUTE SYSTEMS

Germination of lettuce and wheat in soil is reduced by a decrease in water potential, but a significant temperature-water potential interaction exists for lettuce. At 35 C kinetin permits lettuce germination at 0 and —1.1 bars, and at 25 C and 15 C it enhances germination at lower water potentials, causing 30% germination at —8.0 bars. Wheat germinates well at —8.0 bars, but no germination occurs at —14.9 bars; temperature had little effect on wheat germination. Germination in soil and solute systems was compared to determine the usefulness of solute germination data for predicting germination in dry soil. Total germination of lettuce in polyethylene glycol-6000 may approximate total germination in soil at the same water potential, but germination rates differ widely for the two systems. Kinetin-treated lettuce seeds nearly completed germination in two days in polyethylene glycol solutions, but five days were required for similar germination percentages in the soil. Sucrose is not useful for simulating soil water stress; wheat seeds germinate at —14.9 bars in sucrose but fail to germinate in soil at the same potential, and germination is more rapid in sucrose than in the soil.     

光温和化学处理对水青树种子发芽的影响

水青树是一种稀有珍贵树木。它的种子没有休眠,对光的反应随温度而异,25℃时不需光,24—33℃(多在28—30℃)喜光,10—20℃光对发芽有促进作用。最适发芽温度为25℃。经冬季低温层积的种子,可在1.4—8.2℃的低温中发芽。硝酸钾能部分解除种子发芽对温度的要求,GA也略有这种作用。以上结果不仅对水青树的种子检验和播种育苗有实用价值,同时在光温和化学处理对发芽的影响方面,有一定的理论价值。     

THE EFFECTS OF TEMPERATURE ON THE GERMINATION AND RADICLE GROWTH OF PHOTOSENSITIVE LETTUCE SEED

1. The time course of germination of Grand Rapids lettuce seedshas heen followed with different combinations of temperature(3°–35°) and irradiation (red or far-red light).For each set of conditions the following three parameters weredetermined: (i) the time required for half maximum germination,(ii) the rate of germination during the actively germinatingphase, and (iii) the maximum germination attained. In general,as the temperature was lowered, with dark-imbibed seeds, (i)became longer, (ii) became lower, but (iii) became progressivelyhigher. The effect of red light at any temperature was to shorten(i) and increase (ii) and (iii) over the values dark controls.Far-red light exerted an effect opposite to that of red light.Temperatures higher than 25° inhibited (ii) and (iii) underany light conditions. The optimum temperature to the actionof red and far-red light is 25°, at which the stimulatoryeffect of red light and the inhibition of this effect by far-redlight are both maximal. 2. The growth of the radicles of de-coated seeds of Grand Rapidslettuce shows two phases at all temperatures studied. PhaseI is characterized by slow but linear growth which continuesuntil shortly after visible differentiation of the radicle intothe hypocotyl and the root. Phase II is a phase of active growthin which the total length reflects mainly the length of theroot. The optimum temperature for Phase I is 25°-35°,and that, for Phase II is 25°. In neither phase, and atnone of the temperatures studied, is there any effect of redor far-red radiation on the growth of the radicle. The firstvisible sign of radicle elongation in red light induced seeds,however, takes place at exactly the same time as that of germination. 3. Similarities and dissimilarities between the germinationand the growth are pointed out, and it is concluded that thetwo phenomena are different, but proceed at sites closely associatedin the embryo. ¹Present address: Johnson Foundation for Medical Physics, Universityof Pennsylvania, Philadelphia, Pa., U.S.A.     

西双版纳热带雨林中榕树动物群落结构与多样性研究

榕树是西双版纳热带雨林生态系统中的一个关键植物类群,在该类植物中,形成了以榕树果实、叶片、枝杆、枯枝落叶、土壤为食物、栖息、繁殖环境和帮助榕树授粉、传播种子的动物群落;榕树和动物之间形成了互相依赖、协同共存、互保发展的紧密关系。     

光对热带雨林冠层树种绒毛番龙眼种子萌发及其幼苗早期建立的影响

绒毛番龙眼(Pometia tomentosa)为西双版纳热带季节雨林标志树种,被列为中国珍稀濒危植物。对其开展种子及幼苗生态学研究可为珍稀濒危树种的保护及当地森林恢复提供科学依据。试验采用遮荫试验和野外试验相结合的方法,研究光对绒毛番龙眼种子萌发及幼苗早期建立的影响。结果表明:在遮荫试验30%(林窗中心光)、10%(林窗边缘光)和3.5%(林下光)3个光处理及森林3种生境(林窗中心、林窗边缘和林下)条件下,种子萌发率差异无显著性差异,均达到95%以上,且平均萌发周期小于6 d。3个光处理下的幼苗生长、生物量分配模式及气体交换参数差异显著。30%光下绒毛番龙眼幼苗的根重比(RMR)和茎重比(SMR)最高,10%和3.5%光下幼苗的叶重比(LMR)最高,3.5%光下的叶面积比(LAR)显著高于30%光下。30%光下绒毛番龙眼幼苗的最大净光合速率(P_nmax)、暗呼吸速率(R_d)和光饱和点(I_sat)在3个光处理中均最大,光补偿点(I_comp)则无显著性差异。绒毛番龙眼幼苗具耐荫性,能够在低光环境下长期存活且能缓慢生长;同时具有适应林窗光环境生长的能力,如高的质量相对生长速率(RGR_M)和高度相对生长速率(RGR_H)。林窗的出现是绒毛番龙眼进行成功更新的必要条件,水分可能是限制其幼苗生境选择的另一环境因子。     

温湿度和光照对宁夏灌区春小麦白粉病菌分生孢子萌发的影响

在宁夏灌区,春小麦白粉病菌(Erysiphe graminis f.sp.tritici)的分生孢子在-3-29℃温度范围都可萌发。温度达33℃时不能萌发,最适温度为10—15℃。分生孢子虽然在0—100%的湿度下都可以萌发。但以饱和湿度最适。紫外光对分生孢子有强烈的杀伤作用。直射阳光对分生孢子的萌发有抑制作用;在散射光和黑暗条件下,孢子的萌发率没有显着差异。     

GERMINATION AND GROWTH OF BIRD-DISPERSED PLANTS: EFFECTS OF SEED SIZE AND LIGHT ON SEEDLING VIGOR AND BIOMASS ALLOCATION

I examined germination and seedling growth in nine species of fleshy-fruited plants from Washington and Idaho to assess their relative responses to sun and shade. I allowed seeds to germinate over a period of 500 days, and grew the seedlings in a greenhouse for 35 days prior to harvest. Cumulative percentage germination of six species approximated logistic curves. Species with larger seeds were more shade-tolerant, which resulted largely from greater biomass allocation to roots by these species. Seedlings of Rosa gymnocarpa, Sorbus scopulina, Symphoricarpos albus, Clintonia uniflora, and Streptopus amplexifolius grew larger in open sun than in shade (35% open sun), whereas those of Actaea rubra, Disporum trachycarpum, Smilacina racemosa, and Smilacina stellata showed no differences. Percentage root biomass was higher in sun than in shade for R. gymnocarpa, S. scopulina, S. albus, C. uniflora, and S. amplexifolius, but lower for S. stellata. In C. uniflora, S. racemosa, and S. stellata, seeds from unripe fruits failed to germinate. The results suggest that light gaps resulting from periodic disturbance of canopy influence recruitment of bird-dispersed species differentially and thereby contribute to maintaining high species richness and diversity in understories of temperate coniferous forests.     

西双版纳热带季节雨林优势树种树干呼吸特征

 采用红外气体分析法（IRGA）原位监测了西双版纳热带季节雨林11种优势树种树干呼吸速率、1 cm深树干温度以及林内空气变化情况。研究发 现,11种优势树种的树干呼吸具有相同的季节规律,并且雨季均大于干季时的树干呼吸。树种间树干呼吸速率差异显著,在0. 823～2.727 μmol&;#8226;m^-2&;#8226;s^-1。树干1.3 m处所测南北方向树干呼吸无显著性差异。树干呼吸与树干温度显著相关(0.552<0.92),呈良好的自然指数回归关 系,Q₁₀值为1.90～3.03。20 ℃时各树种的RT（总树干呼吸）速率为0.771～2.570μmol&;#8226;m^-2&;#8226;s^-1。     

TEMPERATURE EFFECTS ON SEED GERMINATION OF EAST ASIAN AND TERTIARY RELICT SPECIES OF DIOSCOREA (DIOSCOREACEAE)

To obtain information relevant to the evolution of dormancy, germination responses to temperature of intact seeds and naked zygotic embryos were compared among taxonomically closely related species of Dioscorea in the section Stenophora. We examined five species from the northern half of the East Asian distribution area and four species considered to be Tertiary relict species from the Appalachians, the Caucasus, and the Balkans. Although features of germination of the intact seeds differed from species to species, the naked embryos of all species germinated over a similar wide range of temperatures without any marked differences among species. This unitary physiological feature of the embryos suggests the possibility that the temperature responses of the embryos have not changed since the Tertiary period. In the East Asian species, as the distribution area shifts to the north the seeds gradually lose their dormant features, and consequently the germination behavior of the seeds gradually changes to resemble that of their embryos. The seed of the northernmost species has no dormant features at all, and temperature responses of the seed are the same as those of the embryo. Full germination of the intact seeds of East Asian and Tertiary relict species required prior chilling treatment. Unlike the East Asian species, however, the relict species germinated to some extent at higher temperatures over a narrow range without prior chilling. However, the resultant germlings died or elongated poorly. Thus, the germination process of relict species may have become less sensitive to high-temperature inhibition after their isolation from Asian species.     

西双版纳土地的不同管理方式对植物多样性的影响评价探讨

 现代生物多样性的迅速丧失主要是由于对土地的不合理利用所致,因此对土地的合理利用被认为是生物多样性有效保护的基础。西双版纳是我国植物多样性最丰富的地区之一,然而,由于土地利用的变化,植物多样性也不同程度受到影响。为探讨土地利用对生物多样性的影响,本文在样方调查的基础上,运用定量的方法计算西双版纳主要的土地利用方式对生物多样性的影响指数(I=l/E,E=log10(V3·s·e,r))进行计算,发现对植物多样性的影响依次为：单一的橡胶种植园、橡胶+茶叶、橡胶+菠萝、家庭庭园、寺庙庭园、天然林下砂仁的种植、丢荒(8年)的轮歇地、集体林、龙山林和保护区。因此,要有效保护西双版纳的生物多样性,一是要保护好现存的自然保护区与传统信仰林,二是在土地开发利用时要推广既有较好的经济和社会效益,同时又有较好的生态效益的混农林技术。     

光、温湿度对柑桔木虱发育、繁殖与存活的影响

本研究结果表明,在光照强度为11000lx以下(6小时光照时为15000lx)、每天光照时间在18小时以内,光照强度越大,光照时间越长,柑桔木虱雌成虫的产卵前期越短,产卵量越大,死亡率越低。 温度为15—34℃,相对湿度为43—92％范围内,温湿度对柑桔木虱卵的孵化率影响较小。柑桔木虱若虫在高温(34℃)、高湿(85％,92％)下死亡率高;适温(20—30℃)、低湿(43—75％)下死亡率低。湿度对柑桔木虱卵及若虫发育历期影响不大。在温度为15—34℃范围内,温度与卵及若虫的发育历期呈抛物线关系。柑桔木虱卵及1—5龄若虫的发育起点温度分别是:9.41℃、8.30℃、9.72℃、8.92℃、9.61℃及9.07℃,有效积温分别是:60.03日度、39.78日度、26.82日度,33.23日度及74.49日度。     

沙埋和种子大小对固沙禾草沙鞭的种子萌发与幼苗出土的影响

该文研究了野外条件下不同深度的沙埋对沙鞭(Psammochloa villosa)种子萌发和幼苗出土的影响,以及温室条件下种子大小对不同深度沙埋后的种子萌发和幼苗出土的影响。结果表明,沙埋深度显著影响沙鞭的种子萌发率、幼苗出土率和种子休眠率。沙子表面的种子不能萌发。2 cm的浅层沙埋时的种子萌发率和幼苗出土率最高,1 cm 沙埋的种子萌发率和幼苗出土率次之。沙埋深度超过2 cm之后,沙鞭的种子萌发率和幼苗出土率与沙埋深度呈负相关。2 cm的种子休眠率最低。从2 ~12 cm,种子休眠率随着沙埋深度的增加而增加。在幼苗能够出土的深度(1~6 cm),幼苗首次出土所需的时间随着沙埋深度的增加而延长。种子大小对沙鞭的种子萌发率没有显著影响。但是在深层沙埋(6 cm)时,与小种子相比,大种子产生的幼苗的出土率较高。从2~6 cm,大种子形成的幼苗的茎长度都较长。     

西双版纳不同热带生态系统土壤有机质的光谱学特性

 为了探讨西双版纳地区土地利用变化对土壤有机质含量及其化学组成的影响,选取了相邻的次生林、耕种6年的农田和定植3年的橡胶园样地,对其0～5 cm和5～20 cm表层土壤中有机质含量、胡敏酸的光谱学特性进行了分析。研究结果表明,次生林转变为农田之后,0～5 cm和5～20 cm 表层土壤有机质含量分别降低33.6%和23.7%;而次生林转变为橡胶园,分别降低28.6%和27.6%。胡敏酸可见-红外光谱结果显示,次生林转变为农田和橡胶园后,0～20 cm表层土壤E4/E6显著降低,这表明胡敏酸化学组成当中芳香族结构增加。傅立叶变换红外光谱结果同样表明,土地利用变化影响土壤有机质的化学组成。次生林转变为农田和橡胶园后,胡敏酸中羧基和酚基结构比例降低,而脂肪族、芳香族和多聚糖比例增加。     

低温和光对灌浆期水稻剑叶光合作用的影响

水稻剑叶的光合速率和表观量子效率均随温度的下降而降低,光合速率的下降比表观量子效率的下降明显。低温处理亦引起了最大光合速率和表观量子效率的降低及气孔阻力的升高。这些变化,光照低温处理的大于黑暗低温的;当转入常温后,前者光合速率的恢复慢于后者;恢复期间,有光照的又比无光照的光合速率恢复要慢。     

西双版纳土地利用/覆盖变化与地形的关系

 土地利用/覆盖变化是全球变化研究的重要领域。该文利用6个时期的MSS/TM/ETM影像和1:50 000DEM数据分析了1976~2007年西双版纳地区不同地形下的土地利用/覆盖变化动态, 结果表明: 1)31年间, 该区土地利用/覆盖变化剧烈, 有林地面积由1976年的69.0%下降到2007年的43.6%, 橡胶园面积由1976年的1.3%增加到2007年的11.8%; 2)有林地在海拔1 600 m以下不断减少, 而橡胶园的海拔分布上限则持续增加, 由1976年的1 000 m上升至2007年的1 400 m, 面积在400~1 000 m处占优。农业用地主要分布在海拔400～600 m, 在600 m之上迅速减少; 3)各坡度带上的有林地面积逐年减少, 橡胶园则逐年增加, 而灌木林与旱地则先升后降; 橡胶园、农业用地等主要分布在坡度较缓的区域, 坡度越大, 有林地越多; 1988年后, 橡胶园面积在坡度5°以下基本保持不变, 但在坡度大于5°的区域持续扩张; 4)坡向对橡胶园与农业用地等分布的影响较大, 南坡的橡胶发展最为迅速, 且有向北坡发展的趋势。有林地在北坡分布比例较大, 旱地在北坡分布比例较小。人口增加与橡胶园和茶园等经济种植园的不断扩展是导致西双版纳土地利用/覆盖变化的直接因素。要实现西双版纳的可持续发展, 必须控制经济种植园的盲目扩张, 科学合理垦殖, 保护热带森林。     

西双版纳不同林龄次生植物群落优势树种的热值

该文对西双版纳的4种次生植物群落优势树种的热值进行了研究。4种群落类型分别是山黄麻(Trema orientalis)群落、白背桐(Mallotus paniculatus)群落、中平树(Macaranga denticulata)群落和思茅崖豆(Millettia leptobotrya)群落,群落年龄分别为2、4、6年和大于15年。4种群落各优势树种的平均干重热值分别为19 182.11、19 474.81、19 551.38和19 445.95 J·g^-1。总体来讲,热值随着群落年龄的增加而增加。增长的原因应该是群落光能利用效率的增加。思茅崖豆群落的热值稍有降低,是因为这个群落样地处在阴坡,不能接受到像其它3个群落那样在阳坡的充足光照。先锋树种的热值明显低于顶极树种。可能是因为在群落演替初期,生态系统增加能量耗散的主要方式是通过生物量的增加;而当结构建成,生物量增加到一定程度,已经没有足够增长空间的时候,生态系统将会改变能量储存方式,主要通过单位质量固定能量的增加,也就是热值的增加,来耗散能量。山黄麻群落中叶片的热值非常低,低于根的热值水平,是短命树种将能量更多地投资于繁殖的原因。     

EFFECTS OF TEMPERATURE ON GROWTH,LIGHT ABSORPTION,AND QUANTUM YIELD IN DUNALIELLA TERTIOLECTA (CHLOROPHYCEAE)1

The effects of growth temperature on the marine chlorophyte Dunaliella tertiolecta Butcher were studied to provide a more mechanistic understanding of the role of environmental factors in regulating bio-optical properties of phytoplankton. Specific attention was focused on quantities that are relevant for modeling of growth and photosynthesis. Characteristics including chlorophyll a (chl z)-specific light absorption (a*_ph(λ)), C:chl a ratio, and quantum yield for growth (φ_μ) varied as functions of temperature under conditions of excess light and nutrients. As temperature increased over the range examined (12°-28°C), intracellular concentrations of chl a increased by a factor of 2 and a*_ph(λ) values decreased by more than 50% at blue to green wavelengths. The lower values of a*_ph(λ) were due to both a decrease in the abundance of accessory pigments relative to chl a and an increase in pigment package effects arising from higher intracellular pigment concentrations. Intracellular pigment concentration increased as a consequence of higher cellular pigment quotas combined with lower cell volume. At high growth temperatures, slightly more light was absorbed on a per-cell-C basis, but the dramatic increases in growth rate from μ= 0.5 d^?1 at 12° C to μ= 2.2 d^?1 at 28°C were primarily due to an increase in φ_μ (0.015–0.041 mol C (mol quanta)^?1). By comparison with previous work on this species, we conclude the effects of temperature on a*_ph(λ) and φ_μ are comparable to those observed for light and nutrient limitation. Patterns of variability in a*_ph(λ)and φ_μ as a function of growth rate at different temperatures are similar to those previously documented for this species grown at the same irradiance but under a range of nitrogen-limited conditions. These results are discussed in the context of implications for bio-optical modeling of aquatic primary production by phytoplankton.